2.14. Create Template…

The Create Template… command opens the
“Create New Template” dialog that allows you
to create a template with the same dimensions and color space as
the current image. A dialog pops up, which asks you to
name the new template. Then the template is saved and becomes
available in the New Image
dialog. If you give a name that already exists,
GIMP generates a unique name
by appending a number to it. You can use the
Templates dialog
to modify or delete templates.

2.14.1. Activating the Command

You can access this command from the image menu through
File → Create Template….
There is no default keyboard shortcut.